The Role of Glutathione Reductase in Influenza Infection.

Influenza infection induces lung epithelial cell injury via programmed cell death. Glutathione, a potent antioxidant, has been reported to be associated with influenza infection. We hypothesized that lung epithelial cell death during influenza infection is regulated by glutathione metabolism. Eight-week-old male and female BALB/c mice were infected with influenza (PR8: A/PR/8/34 [H1N1]) via intranasal instillation. Metabolomic analyses were performed on whole lung lysate after influenza infection. For in vitro analysis, Beas-2B cells were infected with influenza. RNA was extracted, and QuantiTect Primer Assay was used to assess gene expression. Glutathione concentrations were assessed by colorimetric assay. Influenza infection resulted in increased inflammation and epithelial cell injury in our murine model, leading to increased morbidity and mortality. In both our in vivo and in vitro models, influenza infection was found to induce apoptosis and necroptosis. Influenza infection led to decreased glutathione metabolism and reduced glutathione reductase activity in lung epithelial cells. Genetic inhibition of glutathione reductase suppressed apoptosis and necroptosis of lung epithelial cells. Pharmacologic inhibition of glutathione reductase reduced airway inflammation, lung injury, and cell death in our murine influenza model. Our results demonstrate that glutathione reductase activity is suppressed during influenza. Glutathione reductase inhibition prevents epithelial cell death and morbidity in our murine influenza model. Our results suggest that glutathione reductase-dependent glutathione metabolism may play an important role in the host response to viral infection by regulating lung epithelial cell death.

Association of circulating cell-free double-stranded DNA and metabolic derangements in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease with unclear aetiology and poorly understood pathophysiology. Although plasma levels of circulating cell-free DNA (ccf-DNA) and metabolomic changes have been reported in IPF, the associations between ccf-DNA levels and metabolic derangements in lung fibrosis are unclear. Here, we demonstrate that ccf-double-stranded DNA (dsDNA) is increased in patients with IPF with rapid progression of disease compared with slow progressors and healthy controls and that ccf-dsDNA associates with amino acid metabolism, energy metabolism and lipid metabolism pathways in patients with IPF.

Antiviral Gene Expression in Young and Aged Murine Lung during H1N1 and H3N2.

Influenza is a respiratory virus that alone or in combination with secondary bacterial pathogens can contribute to the development of acute pneumonia in persons >65 years of age. Host innate immune antiviral signaling early in response to influenza is essential to inhibit early viral replication and guide the initiation of adaptive immune responses. Using young adult (3 months) and aged adult mice infected with mouse adapted H1N1 or H3N2, the results of our study illustrate dysregulated and/or diminished activation of key signaling pathways in aged lung contribute to increased lung inflammation and morbidity. Specifically, within the first seven days of infection, there were significant changes in genes associated with TLR and RIG-I signaling detected in aged murine lung in response to H1N1 or H3N2. Taken together, the results of our study expand our current understanding of age-associated changes in antiviral signaling in the lung.

RIPK3 Activates MLKL-mediated Necroptosis and Inflammasome Signaling during Streptococcus Infection.

Community-acquired pneumonia is the most common type of pneumonia and remains a leading cause of morbidity and mortality worldwide. Although many different pathogens can contribute to pneumonia, Streptococcus pneumoniae is one of the common bacterial pathogens that underlie community-acquired pneumonia. RIPK3 (receptor-interacting protein kinase 3) is widely recognized as a key modulator of inflammation and cell death. To elucidate a potential role of RIPK3 in pneumonia, we examined plasma from healthy control subjects and patients positive for streptococcal pneumonia. In human studies, RIPK3 protein concentrations were significantly elevated and were identified as a potential plasma marker of pneumococcal pneumonia. To expand these findings, we used an in vivo murine model of pneumococcal pneumonia to demonstrate that RIPK3 deficiency leads to reduced bacterial clearance, severe pathological damage, and high mortality. Our results illustrated that RIPK3 forms a complex with RIPK1, MLKL (mixed-lineage kinase domain-like protein), and MCU (mitochondrial calcium uniporter) to induce mitochondrial calcium uptake and mitochondrial reactive oxygen species(mROS) production during S. pneumoniae infection. In macrophages, RIPK3 initiated necroptosis via the mROS-mediated mitochondrial permeability transition pore opening and NLRP3 inflammasome activation via the mROS-AKT pathway to protect against S. pneumoniae. In conclusion, our study demonstrated a mechanism by which RIPK3-initiated necroptosis is essential for host defense against S. pneumoniae.

DROSHA-Dependent miRNA and AIM2 Inflammasome Activation in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease. Chronic lung inflammation is linked to the pathogenesis of IPF. DROSHA, a class 2 ribonuclease III enzyme, has an important role in the biogenesis of microRNA (miRNA). The function of miRNAs has been identified in the regulation of the target gene or protein related to inflammatory responses via degradation of mRNA or inhibition of translation. The absent-in-melanoma-2 (AIM2) inflammasome is critical for inflammatory responses against cytosolic double stranded DNA (dsDNA) from pathogen-associated molecular patterns (PAMPs) and self-DNA from danger-associated molecular patterns (DAMPs). The AIM2 inflammasome senses double strand DNA (dsDNA) and interacts with the adaptor apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), which recruits pro-caspase-1 and regulates the maturation and secretion of interleukin (IL)-1ß and IL-18. A recent study showed that inflammasome activation contributes to lung inflammation and fibrogenesis during IPF. In the current review, we discuss recent advances in our understanding of the DROSHA-miRNA-AIM2 inflammasome axis in the pathogenesis of IPF.

GLUT1-dependent glycolysis regulates exacerbation of fibrosis via AIM2 inflammasome activation.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a rapidly progressive, fatal lung disease that affects older adults. One of the detrimental natural histories of IPF is acute exacerbation of IPF (AE-IPF), of which bacterial infection is reported to play an important role. However, the mechanism by which bacterial infection modulates the fibrotic response remains unclear. OBJECTIVES: Altered glucose metabolism has been implicated in the pathogenesis of fibrotic lung diseases. We have previously demonstrated that glucose transporter 1 (GLUT1)-dependent glycolysis regulates fibrogenesis in a murine fibrosis model. To expand on these findings, we hypothesised that GLUT1-dependent glycolysis regulates acute exacerbation of lung fibrogenesis during bacterial infection via AIM2 inflammasome activation. RESULTS: In our current study, using a murine model of Streptococcus pneumoniae (S. pneumoniae) infection, we investigated the potential role of GLUT1 on mediating fibrotic responses to an acute exacerbation during bleomycin-induced fibrosis. The results of our current study illustrate that GLUT1 deficiency ameliorates S. pneumoniae-mediated exacerbation of lung fibrosis (wild type (WT)/phosphate buffered saline (PBS), n=3; WT/S. pneumoniae, n=3; WT/Bleomycin, n=5 ; WT/Bleomycin+S. pneumoniae, n=7; LysM-Cre-Glut1fl/f /PBS, n=3; LysM-Cre-Glut1fl/fl /S. pneumoniae, n=3; LysM-Cre-Glut1fl/fl /Bleomycin, n=6; LysM-Cre-Glut1fl/fl /Bleomycin+S. pneumoniae, n=9, p=0.041). Further, the AIM2 inflammasome, a multiprotein complex essential for sensing cytosolic bacterial DNA as a danger signal, is an important regulator of this GLUT1-mediated fibrosis and genetic deficiency of AIM2 reduced bleomycin-induced fibrosis after S. pneumoniae infection (WT/PBS, n=6; WT/Bleomycin+S. pneumoniae, n=15; Aim2-/-/PBS, n=6, Aim2-/-/Bleomycin+S. pneumoniae, n=11, p=0.034). GLUT1 deficiency reduced expression and function of the AIM2 inflammasome, and AIM2-deficient mice showed substantial reduction of lung fibrosis after S. pneumoniae infection. CONCLUSION: Our results demonstrate that GLUT1-dependent glycolysis promotes exacerbation of lung fibrogenesis during S. pneumoniae infection via AIM2 inflammasome activation.

DROSHA-Dependent AIM2 Inflammasome Activation Contributes to Lung Inflammation during Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) has been linked to chronic lung inflammation. Drosha ribonuclease III (DROSHA), a class 2 ribonuclease III enzyme, plays a key role in microRNA (miRNA) biogenesis. However, the mechanisms by which DROSHA affects the lung inflammation during idiopathic pulmonary fibrosis (IPF) remain unclear. Here, we demonstrate that DROSHA regulates the absent in melanoma 2 (AIM2) inflammasome activation during idiopathic pulmonary fibrosis (IPF). Both DROSHA and AIM2 protein expression were elevated in alveolar macrophages of patients with IPF. We also found that DROSHA and AIM2 protein expression were increased in alveolar macrophages of lung tissues in a mouse model of bleomycin-induced pulmonary fibrosis. DROSHA deficiency suppressed AIM2 inflammasome-dependent caspase-1 activation and interleukin (IL)-1ß and IL-18 secretion in primary mouse alveolar macrophages and bone marrow-derived macrophages (BMDMs). Transduction of microRNA (miRNA) increased the formation of the adaptor apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks, which is required for AIM2 inflammasome activation in BMDMs. Our results suggest that DROSHA promotes AIM2 inflammasome activation-dependent lung inflammation during IPF.

Mitofusins regulate lipid metabolism to mediate the development of lung fibrosis.

Accumulating evidence illustrates a fundamental role for mitochondria in lung alveolar type 2 epithelial cell (AEC2) dysfunction in the pathogenesis of idiopathic pulmonary fibrosis. However, the role of mitochondrial fusion in AEC2 function and lung fibrosis development remains unknown. Here we report that the absence of the mitochondrial fusion proteins mitofusin1 (MFN1) and mitofusin2 (MFN2) in murine AEC2 cells leads to morbidity and mortality associated with spontaneous lung fibrosis. We uncover a crucial role for MFN1 and MFN2 in the production of surfactant lipids with MFN1 and MFN2 regulating the synthesis of phospholipids and cholesterol in AEC2 cells. Loss of MFN1, MFN2 or inhibiting lipid synthesis via fatty acid synthase deficiency in AEC2 cells exacerbates bleomycin-induced lung fibrosis. We propose a tenet that mitochondrial fusion and lipid metabolism are tightly linked to regulate AEC2 cell injury and subsequent fibrotic remodeling in the lung.

Mitochondrial Dysfunction in Aged Macrophages and Lung during Primary Streptococcus pneumoniae Infection is Improved with Pirfenidone.

Pneumococcal infections remain a leading cause of death in older adults, with the most serious cases occurring in persons ≥65 years of age. There is an urgent need to investigate molecular pathways underlying these impairments and devise new therapeutics to modulate innate immunity. The goal of our current study is to understand the impact of chronological aging on mitochondrial function in response to Streptococcus pneumoniae, a causative agent of bacterial pneumonia. Using chronologically aged murine models, our findings demonstrate that decreased ATP production is associated with dysregulated mitochondrial complex expression, enhanced oxidative stress, diminished antioxidant responses, and decreased numbers of healthy mitochondria in aged adult macrophages and lung in response to S. pneumoniae. Pre-treatment of aged macrophages with pirfenidone, an anti-fibrotic drug with antioxidant and anti-inflammatory properties, improved mitochondrial function and decreased cellular oxidative stress responses. In vivo administration of pirfenidone decreased superoxide formation, increased healthy mitochondria number, improved ATP production, and decreased inflammatory cell recruitment and pulmonary oedema in aged mouse lung during infection. Taken together, our data shed light on the susceptibility of older persons to S. pneumoniae and provide a possible therapeutic to improve mitochondrial responses in this population.

Laminin α1 is a genetic modifier of TGF-ß1-stimulated pulmonary fibrosis.

The pathogenetic mechanisms underlying the pathologic fibrosis in diseases such as idiopathic pulmonary fibrosis (IPF) are poorly understood. To identify genetic factors affecting susceptibility to IPF, we analyzed a murine genetic model of IPF in which a profibrotic cytokine (TGF-ß1) was expressed in the lungs of 10 different inbred mouse strains. Surprisingly, the extent of TGF-ß1-induced lung fibrosis was highly strain dependent. Haplotype-based computational genetic analysis and gene expression profiling of lung tissue obtained from fibrosis-susceptible and -resistant strains identified laminin α1 (Lama1) as a genetic modifier for susceptibility to IPF. Subsequent studies demonstrated that Lama1 plays an important role in multiple processes that affect the pulmonary response to lung injury and susceptibility to fibrosis, which include: macrophage activation, fibroblast proliferation, myofibroblast transformation, and the production of extracellular matrix. Also, Lama1 mRNA expression was significantly increased in lung tissue obtained from IPF patients. These studies identify Lama1 as the genetic modifier of TGF-ß1 effector responses that significantly affects the development of pulmonary fibrosis.

NLRP3 inflammasome activation in aged macrophages is diminished during Streptococcus pneumoniae infection.

Pneumococcal infections are the eigth leading cause of death in the United States, and it is estimated that older patients (≥65 yr of age) account for the most serious cases. The goal of our current study is to understand the impact of biological aging on innate immune responses to Streptococcus pneumoniae, a causative agent of bacterial pneumonia. With the use of in vitro and in vivo aged murine models, our findings demonstrate that age-enhanced unfolded protein responses (UPRs) contribute to diminished inflammasome assembly and activation during S. pneumoniae infection. Pretreatment of aged mice with endoplasmic reticulum chaperone and the stress-reducing agent tauroursodeoxycholic acid (TUDCA) decreased mortality in aged hosts that was associated with increased NLRP3 inflammasome activation, improved pathogen clearance, and decreased pneumonitis during infection. Taken together, our data provide new evidence as to why older persons are more susceptible to S. pneumoniae and provide a possible therapeutic target to decrease morbidity and mortality in this population.

Glucose Transporter 1-Dependent Glycolysis Is Increased during Aging-Related Lung Fibrosis, and Phloretin Inhibits Lung Fibrosis.

Aging is associated with metabolic diseases such as type 2 diabetes mellitus, cardiovascular disease, cancer, and neurodegeneration. Aging contributes to common processes including metabolic dysfunction, DNA damage, and reactive oxygen species generation. Although glycolysis has been linked to cell growth and proliferation, the mechanisms by which the activation of glycolysis by aging regulates fibrogenesis in the lung remain unclear. The objective of this study was to determine if glucose transporter 1 (GLUT1)-induced glycolysis regulates age-dependent fibrogenesis of the lung. Mouse and human lung tissues were analyzed for GLUT1 and glycolytic markers using immunoblotting. Glycolytic function was measured using a Seahorse apparatus. To study the effect of GLUT1, genetic inhibition of GLUT1 was performed by short hairpin RNA transduction, and phloretin was used for pharmacologic inhibition of GLUT1. GLUT1-dependent glycolysis is activated in aged lung. Genetic and pharmacologic inhibition of GLUT1 suppressed the protein expression of α-smooth muscle actin, a key cytoskeletal component of activated fibroblasts, in mouse primary lung fibroblast cells. Moreover, we demonstrated that the activation of AMP-activated protein kinase, which is regulated by GLUT1-dependent glycolysis, represents a critical metabolic pathway for fibroblast activation. Furthermore, we demonstrated that phloretin, a potent inhibitor of GLUT1, significantly inhibited bleomycin-induced lung fibrosis in vivo. These results suggest that GLUT1-dependent glycolysis regulates fibrogenesis in aged lung and that inhibition of GLUT1 provides a potential target of therapy of age-related lung fibrosis.

Age-Dependent Susceptibility to Pulmonary Fibrosis Is Associated with NLRP3 Inflammasome Activation.

Aging has been implicated in the development of pulmonary fibrosis, which has seen a sharp increase in incidence in those older than 50 years. Recent studies demonstrate a role for the nucleotide-binding domain and leucine rich repeat containing family, pyrin domain containing 3 (NLRP3) inflammasome and its regulated cytokines in experimental lung fibrosis. In this study, we tested the hypothesis that age-related NLRP3 inflammasome activation is an important predisposing factor in the development of pulmonary fibrosis. Briefly, young and aged wild-type and NLRP3(-/-) mice were subjected to bleomycin-induced lung injury. Pulmonary fibrosis was determined by histology and hydroxyproline accumulation. Bone marrow and alveolar macrophages were isolated from these mice. NLRP3 inflammasome activation was assessed by co-immunoprecipitation experiments. IL-1ß and IL-18 production was measured by ELISA. The current study demonstrated that aged wild-type mice developed more lung fibrosis and exhibited increased morbidity and mortality after bleomycin-induced lung injury, when compared with young mice. Bleomycin-exposed aged NLRP3(-/-) mice had reduced fibrosis compared with their wild-type age-matched counterparts. Bone marrow-derived and alveolar macrophages from aged mice displayed higher levels of NLRP3 inflammasome activation and caspase-1-dependent IL-1ß and IL-18 production, which was associated with altered mitochondrial function and increased production of reactive oxygen species. Our study demonstrated that age-dependent increases in alveolar macrophage mitochondrial reactive oxygen species production and NLRP3 inflammasome activation contribute to the development of experimental fibrosis.

Chitotriosidase in the Pathogenesis of Inflammation, Interstitial Lung Diseases and COPD.

As a member of 18 glycosyl hydrolase (GH) family, chitotriosidase (Chitinase 1, CHIT1) is a true chitinase mainly expressed in the differentiated and polarized macrophages. CHIT1 is an innate immune mediator that digests the cell walls of chitin-containing eukaryotic pathogens, such as fungi. However, CHIT1 is dysregulated in granulomatous and fibrotic interstitial lung diseases characterized by inflammation and tissue remodeling. These include tuberclosis, sarcoidosis, idiopathic pulmonary fibrosis, scleroderma-associated interstitial lung diseases (SSc-ILD), and chronic obstructive lung diseases (COPD). CHIT1 serum concentration correlates with the progression or the severity of these diseases, suggesting a potential use of CHIT1 as a biomarker or a therapeutic target. Recent studies with genetically modified mice demonstrate that CHIT1 enhances TGF-ß1 receptor expression and signaling, suggesting a role in initiating or amplifying the response to organ injury and repair. This additional CHIT1 activity is independent of its enzymatic activity. These studies suggest that CHIT1 serves a bridging function; it is both an innate immune mediator and a regulator of tissue remodeling. This review will focus on recent data linking CHIT1 to the pathogenesis of inflammation, interstitial lung disease, and COPD.

Lysophosphatidic acid and apolipoprotein A1 predict increased risk of developing World Trade Center-lung injury: a nested case-control study.

RATIONALE: Metabolic syndrome, inflammatory and vascular injury markers measured in serum after World Trade Center (WTC) exposures predict abnormal FEV1. We hypothesized that elevated LPA levels predict FEV1 < LLN. METHODS: Nested case-control study of WTC-exposed firefighters. Cases had FEV1 < LLN. Controls derived from the baseline cohort. Demographics, pulmonary function, serum lipids, LPA and ApoA1 were measured. RESULTS: LPA and ApoA1 levels were higher in cases than controls and predictive of case status. LPA increased the odds by 13% while ApoA1 increased the odds by 29% of an FEV1 < LLN in a multivariable model. CONCLUSIONS: Elevated LPA and ApoA1 are predictive of a significantly increased risk of developing an FEV1 < LLN.

MMP-2 and TIMP-1 predict healing of WTC-lung injury in New York City firefighters.

RATIONALE: After 9/11/2001, most FDNY workers had persistent lung function decline but some exposed workers recovered. We hypothesized that the protease/anti-protease balance in serum soon after exposure predicts subsequent recovery. METHODS: We performed a nested case-control study measuring biomarkers in serum drawn before 3/2002 and subsequent forced expiratory volume at one second (FEV1) on repeat spirometry before 3/2008. Serum was assayed for matrix metalloproteinases (MMP-1,2,3,7,8,9,12 and 13) and tissue inhibitors of metalloproteinases (TIMP-1,2,3,4). The representative sub-cohort defined analyte distribution and a concentration above 75th percentile defined elevated biomarker expression. An FEV1 one standard deviation above the mean defined resistance to airway injury. Logistic regression was adjusted for pre-9/11 FEV1, BMI, age and exposure intensity modeled the association between elevated biomarker expression and above average FEV1. RESULTS: FEV1 in cases and controls declined 10% of after 9/11/2001. Cases subsequently returned to 99% of their pre-exposure FEV1 while decline persisted in controls. Elevated TIMP-1 and MMP-2 increased the odds of resistance by 5.4 and 4.2 fold while elevated MMP-1 decreased it by 0.27 fold. CONCLUSIONS: Resistant cases displayed healing, returning to 99% of pre-exposure values. High TIMP-1 and MMP-2 predict healing. MMP/TIMP balance reflects independent pathways to airway injury and repair after WTC exposure.

One airway: Biomarkers of protection from upper and lower airway injury after World Trade Center exposure.

BACKGROUND: Firefighters exposed to World Trade Center (WTC) dust have developed chronic rhinosinusitis (CRS) and abnormal forced expiratory volume in 1 s (FEV1). Overlapping but distinct immune responses may be responsible for the clinical manifestations of upper and lower airway injury. We investigated whether a panel of inflammatory cytokines, either associated or not associated with WTC-LI, can predict future chronic rhinosinusitis disease and its severity. METHODS: Serum obtained within six months of 9/11/2001 from 179 WTC exposed firefighters presenting for subspecialty evaluation prior to 3/2008 was assayed for 39 cytokines. The main outcomes were medically managed CRS (N = 62) and more severe CRS cases requiring sinus surgery (N = 14). We tested biomarker-CRS severity association using ordinal logistic regression analysis. RESULTS: Increasing serum IL-6, IL-8, GRO and neutrophil concentration reduced the risk of CRS progression. Conversely, increasing TNF-α increased the risk of progression. In a multivariable model adjusted for exposure intensity, increasing IL-6, TNF-α and neutrophil concentration remained significant predictors of progression. Elevated IL-6 levels and neutrophil counts also reduced the risk of abnormal FEV1 but in contrast to CRS, increased TNF-α did not increase the risk of abnormal FEV1. CONCLUSIONS: Our study demonstrates both independent and overlapping biomarker associations with upper and lower respiratory injury, and suggests that the innate immune response may play a protective role against CRS and abnormal lung function in those with WTC exposure.

Chitotriosidase is a biomarker for the resistance to World Trade Center lung injury in New York City firefighters.

PURPOSE: World Trade Center (WTC) exposure caused airflow obstruction years after exposure. Chitinases and IgE are innate and humoral mediators of obstructive airway disease. We investigated if serum expression of chitinases and IgE early after WTC exposure predicts subsequent obstruction. METHODS: With a nested case-control design, 251 FDNY personnel had chitotriosidase, YKL-40 and IgE measured in serum drawn within months of 9/11/2001. The main outcome was subsequent Forced Expiratory Volume after 1 second/Forced Vital Capacity (FEV1/FVC) less than the lower limit of normal (LLN). Cases (N = 125) had abnormal FEV1/FVC whereas controls had normal FEV1/FVC (N = 126). In a secondary analysis, resistant cases (N = 66) had FEV1 (≥107%) one standard deviation above the mean. Logistic regression adjusted for age, BMI, exposure intensity and post-exposure FEV1/FVC modeled the association between early biomarkers and later lung function. RESULTS: Cases and Controls initially lost lung function. Controls recovered to pre-9/11 FEV1 and FVC while cases continue to decline. Cases expressed lower serum chitotriosidase and higher IgE levels. Increase in IgE increased the odds of airflow obstruction and decreased the odds of above average FEV1. Alternately, increasing chitotriosidase decreased the odds of abnormal FEV1/FVC and increased the odds of FEV1 ≥ 107%. Serum YKL-40 was not associated with FEV1/FVC or FEV1 in this cohort. CONCLUSIONS: Increased serum chitotriosidase reduces the odds of developing obstruction after WTC-particulate matter exposure and is associated with recovery of lung function. Alternately, elevated IgE is a risk factor for airflow obstruction and progressive lung function decline.

Cardiovascular biomarkers predict susceptibility to lung injury in World Trade Center dust-exposed firefighters.

Pulmonary vascular loss is an early feature of chronic obstructive pulmonary disease. Biomarkers of inflammation and of metabolic syndrome predict loss of lung function in World Trade Center (WTC) lung injury (LI). We investigated if other cardiovascular disease (CVD) biomarkers also predicted WTC-LI. This nested case-cohort study used 801 never-smoker, WTC-exposed firefighters with normal pre-9/11 lung function presenting for subspecialty pulmonary evaluation (SPE) before March 2008. A representative subcohort of 124 out of 801 subjects with serum drawn within 6 months of 9/11 defined CVD biomarker distribution. Post-9/11 forced expiratory volume in 1 s (FEV1) at defined cases were as follows: susceptible WTC-LI cases with FEV1 ≤77% predicted (66 out of 801) and resistant WTC-LI cases with FEV1 ≥107% predicted (68 out of 801). All models were adjusted for WTC exposure intensity, body mass index at SPE, age on 9/11 and pre-9/11 FEV1. Susceptible WTC-LI cases had higher levels of apolipoprotein-AII, C-reactive protein and macrophage inflammatory protein-4 with significant relative risks (RRs) of 3.85, 3.93 and 0.26, respectively, with an area under the curve (AUC) of 0.858. Resistant WTC-LI cases had significantly higher soluble vascular cell adhesion molecule and lower myeloperoxidase, with RRs of 2.24 and 2.89, respectively (AUC 0.830). Biomarkers of CVD in serum 6 months post-9/11 predicted either susceptibility or resistance to WTC-LI. These biomarkers may define pathways either producing or protecting subjects from pulmonary vascular disease and associated loss of lung function after an irritant exposure.

Comparison of WTC dust size on macrophage inflammatory cytokine release in vivo and in vitro.

BACKGROUND: The WTC collapse exposed over 300,000 people to high concentrations of WTC-PM; particulates up to ∼50 mm were recovered from rescue workers' lungs. Elevated MDC and GM-CSF independently predicted subsequent lung injury in WTC-PM-exposed workers. Our hypotheses are that components of WTC dust strongly induce GM-CSF and MDC in AM; and that these two risk factors are in separate inflammatory pathways. METHODOLOGY/PRINCIPAL FINDINGS: Normal adherent AM from 15 subjects without WTC-exposure were incubated in media alone, LPS 40 ng/mL, or suspensions of WTC-PM(10-53) or WTC-PM(2.5) at concentrations of 10, 50 or 100 µg/mL for 24 hours; supernatants assayed for 39 chemokines/cytokines. In addition, sera from WTC-exposed subjects who developed lung injury were assayed for the same cytokines. In the in vitro studies, cytokines formed two clusters with GM-CSF and MDC as a result of PM(10-53) and PM(2.5). GM-CSF clustered with IL-6 and IL-12(p70) at baseline, after exposure to WTC-PM(10-53) and in sera of WTC dust-exposed subjects (n = 70) with WTC lung injury. Similarly, MDC clustered with GRO and MCP-1. WTC-PM(10-53) consistently induced more cytokine release than WTC-PM(2.5) at 100 µg/mL. Individual baseline expression correlated with WTC-PM-induced GM-CSF and MDC. CONCLUSIONS: WTC-PM(10-53) induced a stronger inflammatory response by human AM than WTC-PM(2.5). This large particle exposure may have contributed to the high incidence of lung injury in those exposed to particles at the WTC site. GM-CSF and MDC consistently cluster separately, suggesting a role for differential cytokine release in WTC-PM injury. Subject-specific response to WTC-PM may underlie individual susceptibility to lung injury after irritant dust exposure.